U.S. patent application number 14/100281 was filed with the patent office on 2014-04-10 for method and apparatus for handling inter-cell interference.
This patent application is currently assigned to HUAWEI TECHNOLOGIES CO., LTD.. The applicant listed for this patent is HUAWEI TECHNOLOGIES CO., LTD.. Invention is credited to Xinrui Feng, Jianqin Liu, Wei Sun, Lei Wan, Yong Wu.
Application Number | 20140098783 14/100281 |
Document ID | / |
Family ID | 47295494 |
Filed Date | 2014-04-10 |
United States Patent
Application |
20140098783 |
Kind Code |
A1 |
Wan; Lei ; et al. |
April 10, 2014 |
METHOD AND APPARATUS FOR HANDLING INTER-CELL INTERFERENCE
Abstract
The present invention discloses a method including: obtaining
downtilt coordination information of a local cell and downtilt
coordination information of a neighbor cell; and setting, according
to the downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell, a downtilt
of a time-frequency resource block on an antenna of the local cell
with respect to a to-be-coordinated user equipment. The downtilt
coordination information of the local cell and that of the neighbor
cell are referenced to for setting the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment, which avoids
interference on user equipments within a service range of the
neighbor cell while ensuring signal received power and SINR
experience for user equipments within a service range of the local
cell.
Inventors: |
Wan; Lei; (Beijing, CN)
; Feng; Xinrui; (Beijing, CN) ; Wu; Yong;
(Beijing, CN) ; Liu; Jianqin; (Beijing, CN)
; Sun; Wei; (Beijing, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HUAWEI TECHNOLOGIES CO., LTD. |
Shenzhen |
|
CN |
|
|
Assignee: |
HUAWEI TECHNOLOGIES CO.,
LTD.
Shenzhen
CN
|
Family ID: |
47295494 |
Appl. No.: |
14/100281 |
Filed: |
December 9, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/CN2012/076703 |
Jun 11, 2012 |
|
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14100281 |
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Current U.S.
Class: |
370/330 |
Current CPC
Class: |
H04W 16/28 20130101;
H04L 5/0073 20130101; H04L 5/0026 20130101; H04W 72/046
20130101 |
Class at
Publication: |
370/330 |
International
Class: |
H04L 5/00 20060101
H04L005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2011 |
CN |
201110154192.8 |
Claims
1. A method for handling inter-cell interference, comprising:
obtaining downtilt coordination information of a local cell and
downtilt coordination information of a neighbor cell; and setting,
according to the downtilt coordination information of the local
cell and the downtilt coordination information of the neighbor
cell, a downtilt of a time-frequency resource block on an antenna
of the local cell with respect to a to-be-coordinated user
equipment; wherein: either downtilt coordination information of the
downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell comprises
any one or more of: optimal downtilt information of time-frequency
resource blocks on an antenna of a cell with respect to user
equipments within a service range of the cell, location information
of user equipments within the service range of the cell, location
information of a base station of the cell, use probabilities of
downtilts on each time-frequency resource block on the antenna of
the cell, probabilities that each time-frequency resource block on
the base station of the cell is assigned to different user
equipments, and downtilts not recommended for time-frequency
resource blocks on an antenna of a neighboring cell.
2. The method according to claim 1, wherein obtaining optimal
downtilt information of the time-frequency resource block on the
antenna of the local cell with respect to a user equipment within a
service range of the local cell comprises: obtaining a direction of
arrival parameter of the user equipment within the service range of
the local cell, wherein the direction of arrival parameter at least
comprises downtilt information of a time-frequency resource block
on the antenna of the local cell with respect to user equipments
within the service range of the local cell, and determining the
optimal downtilt information of the time-frequency resource block
on the antenna of the local cell with respect to the user
equipments within the service range of the local cell according to
the direction of arrival parameter.
3. The method according to claim 2, wherein the obtaining the
direction of arrival parameter of the user equipment within the
service range of the local cell comprises: transmitting channel
state information reference signals of different direction of
arrival parameters to the user equipment within the service range
of the local cell on pilot resource elements within the
time-frequency resource block on the antenna of the local cell, and
receiving a direction of arrival parameter that is returned by the
user equipment within the service range of the local cell and
corresponding to a reference signal whose signal received strength
measured on the reference signal is greater than a preset
threshold; or transmitting reference signals to the user equipment
within the service range of the local cell on pilot resource
elements within the time-frequency resource block on the antenna of
the local cell in a time division, frequency division, or code
division mode; receiving a pre-code matrix of a channel state that
is obtained by the user equipment within the service range of the
local cell by estimation according to the reference signals; and
obtaining the direction of arrival parameter of the user equipment
within the service range of the local cell by estimation according
to the pre-code matrix; or obtaining the direction of arrival
parameter of the user equipment within the service range of the
local cell by estimation according to an uplink channel quality
measurement reference signal reported by the user equipment within
the service range of the local cell.
4. The method according to claim 1, wherein obtaining location
information of the user equipment within the service range of the
local cell comprises: obtaining the direction of arrival parameter
of the user equipment within the service range of the local cell by
estimation according to the uplink channel quality measurement
reference signal reported by the user equipment within the service
range of the local cell, wherein the direction of arrival parameter
at least comprises downtilt information of the time-frequency
resource block on the antenna of the local cell with respect to
user equipments within the service range of the cell; and obtaining
the location information of the user equipment within the service
range of the local cell by calculation according to the direction
of arrival parameter; or receiving location information that is
obtained by the user equipment within the service range of the
local cell by performing positioning according to a predetermined
positioning technology.
5. The method according to claim 1, wherein obtaining downtilts not
recommended by the local cell for time-frequency resource blocks on
an antenna of a neighboring cell comprises: receiving downtilt
information, reported by at least one user equipment served by the
local cell, of a time-frequency resource block on an antenna of the
neighbor cell with respect to the at least one user equipment, and
selecting the downtilts not recommended by the local cell for
time-frequency resource blocks on an antenna of a neighboring cell
from the downtilt information of the time-frequency resource block
on the antenna of the neighbor cell with respect to the at least
one user equipment.
6. The method according to claim 1, wherein the obtaining the
downtilt coordination information of the neighbor cell comprises:
receiving the downtilt coordination information of the neighbor
cell sent by the neighbor cell.
7. The method according to claim 1, wherein obtaining downtilts not
recommended by the neighbor cell for time-frequency resource blocks
on an antenna of a neighboring cell comprises: obtaining a
direction of arrival parameter of a user equipment within a service
range of the neighbor cell, wherein the direction of arrival
parameter at least comprises downtilt information of a
time-frequency resource block on the antenna of the local cell with
respect to user equipments within the service range of the neighbor
cell, and determining, according to the direction of arrival
parameter, the downtilts not recommended by the neighbor cell for
the time-frequency resource blocks on the antenna of the
neighboring cell.
8. The method according to claim 7, wherein the obtaining the
direction of arrival parameter of the user equipment within the
service range of the neighbor cell comprises: transmitting channel
state information reference signals of different direction of
arrival parameters to the user equipment within the service range
of the neighbor cell on pilot resource elements within the
time-frequency resource block on the antenna of the local cell, and
receiving a direction of arrival parameter that is returned by the
user equipment within the service range of the neighbor cell and
corresponding to a reference signal whose signal received strength
measured on the reference signal is greater than a preset
threshold; or transmitting reference signals to the user equipment
within the service range of the neighbor cell on pilot resource
elements within the time-frequency resource block on the antenna of
the local cell in a time division, frequency division, or code
division mode; receiving a pre-code matrix of a channel state
obtained by the user equipment within the service range of the
neighbor cell by estimation according to the reference signals; and
obtaining the direction of arrival parameter of the user equipment
within the service range of the neighbor cell by estimation
according to the pre-code matrix; or obtaining the direction of
arrival parameter of the user equipment within the service range of
the antenna of the neighbor cell by estimation according to an
uplink channel quality measurement reference signal reported by the
user equipment within the service range of the antenna of the
neighbor cell.
9. The method according to claim 1, wherein the setting, according
to the downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell, the
downtilt of the time-frequency resource block on the antenna of the
local cell with respect to the to-be-coordinated user equipment
comprises: determining a range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell according to the downtilt coordination information of
the local cell and the downtilt coordination information of the
neighbor cell; and setting the downtilt of the time-frequency
resource block on the antenna of the local cell with respect to the
to-be-coordinated user equipment according to the range of usable
downtilts based on a preset rule.
10. The method according to claim 9, wherein the determining the
range of usable downtilts for the time-frequency resource blocks on
the antenna of the local cell with respect to the user equipments
within the service range of the local cell according to the
downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell comprises:
determining a range of optimal downtilts for the time-frequency
resource blocks on the antenna of the local cell with respect to
the user equipments within the service range of the local cell
according to the optimal downtilt information, in the downtilt
coordination information of the local cell, of the time-frequency
resource blocks on the antenna of the local cell with respect to
the user equipments within the service range of the local cell; and
using a range of downtilts within the range of optimal downtilts,
excluding downtilts which are in the downtilt coordination
information of the neighbor cell and are not recommended for a
neighboring cell, as the range of usable downtilts for the
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell; or obtaining a distance between a base station of the
local cell and a base station of the neighbor cell by calculation
according to location information of the base station of the
neighbor cell in the neighbor cell coordination information and
location information of the base station of the local cell in the
local cell coordination information, and obtaining the range of
usable downtilts for the time-frequency resource blocks on the
antenna of the local cell with respect to the user equipments
within the service range of the local cell by calculation according
to the distance and a vertical main beam width of the antenna of
the local cell based on a geometrical relationship; or determining
a range of optimal downtilts for the time-frequency resource blocks
on the antenna of the local cell with respect to the user
equipments within the service range of the local cell according to
optimal downtilt information, in the downtilt coordination
information of the local cell, of the time-frequency resource
blocks on the antenna of the local cell with respect to the user
equipments within the service range of the local cell; obtaining a
set comprising neighbor cell downtilts whose use probabilities
exceed a first threshold according to use probabilities, in the
downtilt coordination information of the neighbor cell, of
downtilts of the antenna of the neighbor cell on the time-frequency
resource blocks; according to location information of the base
station of the neighbor cell and location information of the base
station of the local cell, calculating a downtilt set B of the
antenna of the local cell with respect to geographical locations
corresponding to the set comprising the neighbor cell downtilts;
and using a range of downtilts within the range of optimal
downtilts, excluding downtilts in the set B, as the range of usable
downtilts for the time-frequency resource blocks on the antenna of
the local cell with respect to the user equipments within the
service range of the local cell; or determining a range of optimal
downtilts for the time-frequency resource blocks on the antenna of
the local cell with respect to the user equipments within the
service range of the local cell according to optimal downtilt
information, in the downtilt coordination information of the local
cell, of the time-frequency resource blocks on the antenna of the
local cell with respect to the user equipments within the service
range of the local cell; according to location information, in the
downtilt coordination information of the neighbor cell, of UEs
within the service range of the neighbor cell and location
information of the base station of the local cell, calculating a
downtilt set C of the antenna of the local cell with respect to the
location information of the UEs of the neighbor cell; or according
to optimal downtilt information of the time-frequency resource
blocks on the antenna of the neighbor cell with respect to user
equipments within the service range of the neighbor cell and the
location information of the base station of the neighbor cell,
calculating geographical locations corresponding to the optimal
downtilts, and according to the geographical locations
corresponding to the optimal downtilts and the location information
of the base station of the local cell, calculating a downtilt set C
of the antenna of the local cell with respect to the geographical
locations corresponding to the optimal downtilts; and using a range
of downtilts within the range of optimal downtilts, excluding
downtilts in the set C, as the range of usable downtilts for the
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell; or determining a range of optimal downtilts for the
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell according to optimal downtilt information, in the
downtilt coordination information of the local cell, of the
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell; according to probabilities, in the downtilt
coordination information of the neighbor cell, that each
time-frequency resource block on the base station of the neighbor
cell is assigned to different user equipments, searching for a user
equipment whose probability of being assigned with a time-frequency
resource block of the neighbor cell is greater than a second
threshold, and according to location information of the found UE
and the location information of the base station of the local cell,
calculating a downtilt set D of the antenna of the local cell with
respect to the location information of the found UE; or according
to optimal downtilt information of time-frequency resource blocks
on the antenna of the neighbor cell with respect to the found UE
and the location information of the base station of the neighbor
cell, calculating geographical locations corresponding to the
optimal downtilts, and according to the geographical locations
corresponding to the optimal downtilts and the location information
of the base station of the local cell, calculating a downtilt set D
of the antenna of the local cell with respect to the geographical
locations corresponding to the optimal downtilts; and using a range
of downtilts within the range of optimal downtilts, excluding
downtilts in the set D, as the range of usable downtilts for the
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell.
11. The method according to claim 9, wherein the setting the
downtilt of the time-frequency resource block on the antenna of the
local cell with respect to the to-be-coordinated user equipment
according to the range of usable downtilts based on the preset rule
comprises: obtaining optimal downtilt information of the
to-be-coordinated user equipment from the optimal downtilt
information, in the local cell coordination information, of
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell; traversing all usable downtilts in the range of usable
downtilts to find a usable downtilt that is closest to the optimal
downtilt of the to-be-coordinated user equipment; and setting the
downtilt of the time-frequency resource block on the antenna of the
local cell with respect to the to-be-coordinated user equipment to
the usable downtilt that is closest to the optimal downtilt of the
to-be-coordinated user equipment; or traversing all usable
downtilts in the range of usable downtilts to find a usable
downtilt that allows the to-be-coordinated user equipment to have a
greatest signal received power, and setting the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment to the usable
downtilt that allows the to-be-coordinated user equipment to have
the greatest signal received power; or traversing all usable
downtilts in the range of usable downtilts to find a usable
downtilt that allows a greatest signal-to-leakage-and-noise ratio,
and setting the downtilt of the time-frequency resource block on
the antenna of the local cell with respect to the to-be-coordinated
user equipment to the usable downtilt that allows the greatest
signal-to-leakage-and-noise ratio; or traversing all usable
downtilts in the range of usable downtilts to find a usable
downtilt that allows a greatest sum of
signal-to-interference-plus-noise ratios, and setting the downtilt
of the time-frequency resource block on the antenna of the local
cell with respect to the to-be-coordinated user equipment to the
usable downtilt that allows the greatest sum of
signal-to-interference-plus-noise ratios.
12. The method according to claim 1, further comprising:
classifying user equipments within the service range of the local
cell, and assigning a time-frequency resource block on the antenna
of the local cell to the to-be-coordinated user equipment according
to the classification information of user equipments within the
service range of the local cell, based on a fractional frequency
reuse FFR scheduling principle or a soft frequency reuse SFR
scheduling principle; or classifying user equipments within the
service range of the local cell, and assigning a time-frequency
resource block on the antenna of the local cell to the
to-be-coordinated user equipment according to the classification
information of user equipments within the service range of the
local cell and the use probabilities, in the neighbor cell
coordination information, of downtilts on each time-frequency
resource block on the antenna of the neighbor cell, based on a
self-defined dynamic scheduling principle.
13. The method according to claim 12, wherein the classifying user
equipments within the service range of the local cell comprises:
classifying the user equipments within the service range of the
local cell according to the optimal downtilt information, in the
downtilt coordination information of the local cell, of the
time-frequency resource blocks on the antenna of the local cell
with respect to the user equipments within the service range of the
local cell, based on a pre-defined assignment rule; or classifying
the user equipments within the service range of the local cell
according to the location information, in the downtilt coordination
information of the local cell, of the user equipments within the
service range of the local cell.
14. An apparatus for handling inter-cell interference, comprising
an obtaining module and a setting module, wherein: the obtaining
module is configured to obtain downtilt coordination information of
a local cell and downtilt coordination information of a neighbor
cell, wherein either downtilt coordination information of the
downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell comprises
one or more of: optimal downtilt information of time-frequency
resource blocks on an antenna of a cell with respect to user
equipments within a service range of the cell, location information
of user equipments within the service range of the cell, location
information of a base station of the cell, use probabilities of
downtilts on each time-frequency resource block on the antenna of
the cell, probabilities that each time-frequency resource block on
the base station of the cell is assigned to different user
equipments, and downtilts not recommended for time-frequency
resource blocks on an antenna of a neighboring cell; and the
setting module is configured to set, according to the downtilt
coordination information of the local cell and the downtilt
coordination information of the neighbor cell obtained by the
obtaining module, a downtilt of a time-frequency resource block on
the antenna of the local cell with respect to a to-be-coordinated
user equipment.
15. The apparatus according to claim 14, wherein the obtaining
module comprises: a first obtaining unit, configured to obtain a
direction of arrival parameter of a user equipment within a service
range of the local cell, wherein the direction of arrival parameter
at least comprises downtilt information of a time-frequency
resource block on the antenna of the local cell with respect to
user equipments within the service range of the local cell; and a
determining unit, configured to determine, according to the
direction of arrival parameter obtained by the first obtaining
unit, optimal downtilt information of the time-frequency resource
block on the antenna of the local cell with respect to user
equipments within the service range of the local cell.
16. The apparatus according to claim 15, wherein the first
obtaining unit is specifically configured to transmit channel state
information reference signals of different direction of arrival
parameters to the user equipment within the service range of the
local cell on pilot resource elements within the time-frequency
resource block on the antenna of the local cell, and receive a
direction of arrival parameter that is returned by the user
equipment within the service range of the local cell and
corresponding to a reference signal whose signal received strength
measured on the reference signal is greater than a preset
threshold; or the first obtaining unit is specifically configured
to transmit reference signals to the user equipment within the
service range of the local cell on pilot resource elements within
the time-frequency resource block on the antenna of the local cell
in a time division, frequency division, or code division mode;
receive a pre-code matrix of a channel state that is obtained by
the user equipment within the service range of the local cell by
estimation according to the reference signals; and obtain the
direction of arrival parameter of the user equipment within the
service range of the local cell by estimation according to the
pre-code matrix; or the first obtaining unit is specifically
configured to obtain the direction of arrival parameter of the user
equipment within the service range of the local cell by estimation
according to an uplink channel quality measurement reference signal
reported by the user equipment within the service range of the
local cell.
17. The apparatus according to claim 14, wherein the obtaining
module comprises: a second obtaining unit, configured to obtain the
direction of arrival parameter of the user equipment within the
service range of the local cell by estimation according to the
uplink channel quality measurement reference signal reported by the
user equipment within the service range of the local cell, wherein
the direction of arrival parameter at least comprises downtilt
information of the time-frequency resource block on the antenna of
the local cell with respect to user equipments within the service
range of the cell; and obtain location information of the user
equipment within the service range of the local cell by calculation
according to the direction of arrival parameter; or a third
obtaining unit, configured to receive location information that is
obtained by the user equipment within the service range of the
local cell by performing positioning according to a predetermined
positioning technology.
18. The apparatus according to claim 14, wherein the obtaining
module comprises: a fourth obtaining unit, configured to receive
downtilt information, reported by at least one user equipment
served by the local cell, of a time-frequency resource block on an
antenna of the neighbor cell with respect to the at least one user
equipment, and select downtilts not recommended by the local cell
for time-frequency resource blocks on an antenna of a neighboring
cell from the downtilt information of the time-frequency resource
block on the antenna of the neighbor cell with respect to the at
least one user equipment.
19. The apparatus according to claim 14, wherein the obtaining
module comprises: a receiving unit, configured to receive the
downtilt coordination information of the neighbor cell sent by the
neighbor cell.
20. The apparatus according to claim 14, wherein the obtaining
module comprises: a fifth obtaining unit, configured to obtain a
direction of arrival parameter of a user equipment within a service
range of the neighbor cell, wherein the direction of arrival
parameter at least comprises downtilt information of a
time-frequency resource block on the antenna of the neighbor cell
with respect to user equipments within the service range of the
neighbor cell, and determine optimal downtilt information of the
time-frequency resource block on the antenna of the neighbor cell
with respect to user equipments within the service range of the
neighbor cell according to the direction of arrival parameter.
Description
CROSS-REFERENCE TO RELEVANT APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/CN2012/076703, filed on Jun. 11, 2012, which
claims priority to Chinese Patent Application No. 201110154192.8,
filed on Jun. 9, 2011, both of which are hereby incorporated by
reference in their entireties.
TECHNICAL FIELD
[0002] The present invention relates to the field of
communications, and in particular, to a method and an apparatus for
handling inter-cell interference.
BACKGROUND
[0003] As shown in FIG. 1, a downtilt is a direction of an antenna
vertical main beam. Generally, when the downtilt of an antenna is
aligned to a UE (User Equipment, user equipment), the UE has a best
signal received power and best signal received quality.
[0004] At present, an AAS (Active Antenna System, active antenna
system) is capable of electrically adjusting a downtilt in
milliseconds based on subcarriers, which may align a downtilt on
each time-frequency resource block of an antenna to a target UE, to
improve a signal received power and enhance signal received quality
of the target UE.
[0005] However, as shown in FIG. 2, when UEs are distributed evenly
in terms of geographical location, elevation angles of most UEs are
smaller than a downtilt that is set for each cell antenna which
uses the same downtilt. In order to align the downtilt set on each
time-frequency resource block of an antenna to a target UE, the
downtilt set by the AAS system will make a vertical beam on each
time-frequency resource block to further point to a cell edge.
Hence, in a co-frequency networking system, an interfering power of
a local cell on signals of UEs in a neighbor cell increases, which
affects SINR (Signal-to-Interference Plus Noise Ratio,
signal-to-interference-plus-noise ratio) experience of UEs in the
cells.
SUMMARY
[0006] In order to solve the above problem and achieve the purpose
of avoiding interference on a UE in a neighbor cell while ensuring
the received signal strength of a UE in a local cell, embodiments
of the present invention provide a method and an apparatus for
handling inter-cell interference. The technical solutions are as
follows.
[0007] A method for handling inter-cell interference, where the
method includes:
[0008] obtaining downtilt coordination information of a local cell
and downtilt coordination information of a neighbor cell; and
[0009] setting, according to the downtilt coordination information
of the local cell and the downtilt coordination information of the
neighbor cell, a downtilt of a time-frequency resource block on an
antenna of the local cell with respect to a to-be-coordinated user
equipment; where
[0010] either downtilt coordination information of the downtilt
coordination information of the local cell and the downtilt
coordination information of the neighbor cell includes any one or
more of: optimal downtilt information of time-frequency resource
blocks on an antenna of a cell with respect to user equipments
within a service range of the cell, location information of user
equipments within the service range of the cell, location
information of a base station of the cell, use probabilities of
downtilts on each time-frequency resource block on the antenna of
the cell, probabilities that each time-frequency resource block of
the base station of the cell is assigned to different user
equipments, and downtilts not recommended for time-frequency
resource blocks on an antenna of a neighboring cell.
[0011] An apparatus for handling inter-cell interference, where the
apparatus includes an obtaining module and a setting module,
where
[0012] the obtaining module is configured to obtain downtilt
coordination information of a local cell and downtilt coordination
information of a neighbor cell, where either downtilt coordination
information of the downtilt coordination information of the local
cell and the downtilt coordination information of the neighbor cell
includes one or more of: optimal downtilt information of
time-frequency resource blocks on an antenna of a cell with respect
to user equipments within a service range of the cell, location
information of user equipments within the service range of the
cell, location information of a base station of the cell, use
probabilities of downtilts on each time-frequency resource block on
the antenna of the cell, probabilities that each time-frequency
resource block of the base station of the cell is assigned to
different user equipments, and downtilts not recommended for
time-frequency resource blocks on an antenna of a neighboring cell;
and
[0013] the setting module is configured to set, according to the
downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell obtained by
the obtaining module, a downtilt of a time-frequency resource block
on an antenna of the local cell with respect to a to-be-coordinated
user equipment.
[0014] The benefits provided by the technical solutions according
to the embodiments of the present invention are that: by
implementing the technical solutions of obtaining downtilt
coordination information of a local cell and downtilt coordination
information of a neighbor cell, and then setting, according to the
downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell, a downtilt
of a time-frequency resource block on an antenna of the local cell
with respect to a to-be-coordinated user equipment, the downtilt
coordination information of the local cell and that of the neighbor
cell are referenced to for setting the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment, which avoids
interference on user equipments within a service range of the
neighbor cell while ensuring a signal received power and SINR
experience for user equipments within a service range of the local
cell.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a schematic diagram of a downtilt of an antenna in
a prior art of the present invention;
[0016] FIG. 2 is a schematic diagram of an elevation angle of a UE
in a prior art of the present invention;
[0017] FIG. 3 is a flowchart of a method for handling inter-cell
interference according to an embodiment of the present
invention;
[0018] FIG. 4 is a flowchart of another method for handling
inter-cell interference according to an embodiment of the present
invention;
[0019] FIG. 5 is a schematic DOA diagram of a user equipment
according to an embodiment of the present invention;
[0020] FIG. 6 is a schematic diagram of a method for measuring a
three-dimensional pre-code matrix according to an embodiment of the
present invention;
[0021] FIG. 7 is a schematic diagram of transmitting different
downlink CSI-RSs to a user equipment according to an embodiment of
the present invention;
[0022] FIG. 8 is a schematic diagram of a method for calculating a
downtilt set according to an embodiment of the present invention;
and
[0023] FIG. 9 is a block diagram of an apparatus for handling
inter-cell interference according to an embodiment of the present
invention.
DESCRIPTION OF EMBODIMENTS
[0024] To make the objectives, technical solutions, and advantages
of the present invention more comprehensible, the following further
describes the embodiments of the present invention in detail with
reference to the accompanying drawings.
[0025] Referring to FIG. 3, an embodiment of the present invention
provides a method for handling inter-cell interference. The
executing entities of the method include a serving base station or
a network node, and the embodiment of the present invention sets no
specific limit thereto. The method includes the following:
[0026] Step 101: Obtain downtilt coordination information of a
local cell and downtilt coordination information of a neighbor
cell.
[0027] Step 102: Set, according to the downtilt coordination
information of the local cell and the downtilt coordination
information of the neighbor cell, a downtilt of a time-frequency
resource block on an antenna of the local cell with respect to a
to-be-coordinated user equipment.
[0028] Either downtilt coordination information of the downtilt
coordination information of the local cell and the downtilt
coordination information of the neighbor cell includes any one or
more of: optimal downtilt information of time-frequency resource
blocks on an antenna of a cell with respect to user equipments
within a service range of the cell, location information of user
equipments within the service range of the cell, location
information of a base station of the cell, use probabilities of
downtilts on each time-frequency resource block on the antenna of
the cell, probabilities that each time-frequency resource block of
the base station of the cell is assigned to different user
equipments, and downtilts not recommended for time-frequency
resource blocks on an antenna of a neighboring cell.
[0029] By implementing the technical solution of obtaining downtilt
coordination information of a local cell and downtilt coordination
information of a neighbor cell, and then setting, according to the
downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell, a downtilt
of a time-frequency resource block on an antenna of the local cell
with respect to a to-be-coordinated user equipment, the downtilt
coordination information of the local cell and that of the neighbor
cell are referenced to for setting the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment, which avoids
interference on user equipments within a service range of the
neighbor cell while ensuring signal received powers and SINR
experience for user equipments within a service range of the local
cell.
[0030] The method for handling inter-cell interference is described
in detail as follows. The executing entities of the method include
a serving base station or a network node, and the embodiment of the
present invention sets no specific limit thereto. The embodiment of
the present invention presents the related description by using a
base station as an executing entity of the method. Referring to
FIG. 4, the specific method is as follows.
[0031] Step 201: A base station of a local cell obtains downtilt
coordination information of the local cell and downtilt
coordination information of a neighbor cell.
[0032] Either downtilt coordination information of the downtilt
coordination information of the local cell and the downtilt
coordination information of the neighbor cell includes any one or
more of: optimal downtilt information of time-frequency resource
blocks on an antenna of a cell with respect to user equipments
within a service range of the cell, location information of user
equipments within the service range of the cell, location
information of a base station of the cell, use probabilities of
downtilts on each time-frequency resource block on the antenna of
the cell, probabilities that each time-frequency resource block of
the base station of the cell is assigned to different user
equipments, and downtilts not recommended for time-frequency
resource blocks on an antenna of a neighboring cell.
[0033] In particular, this step specifically includes the following
operations.
[0034] Step 201-1: The base station of the local cell obtains the
downtilt coordination information of the local cell, where the
downtilt coordination information of the local cell includes:
optimal downtilt information of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within a service range of the local cell, location information of
user equipments within the service range of the local cell,
location information of the base station of the local cell, use
probabilities of downtilts on each time-frequency resource block on
the antenna of the local cell, probabilities that each
time-frequency resource block of the base station of the local cell
is assigned to different user equipments, and downtilts not
recommended for time-frequency resource blocks on an antenna of a
neighboring cell.
[0035] Obtaining, by the base station of the local cell, the
optimal downtilt information of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell includes the following
operations.
[0036] Step 201-1-1: The base station of the local cell obtains a
DOA (direction of arrival) information of a user equipment within
the service range of the antenna of the local cell, where the DOA
parameter at least includes downtilt information of a
time-frequency resource block on the antenna of the local cell with
respect to user equipments within the service range of the local
cell. In the embodiment of the present invention, the DOA parameter
may also include azimuth angle information of a time-frequency
resource block on the antenna of the local cell with respect to
user equipments within the service range of the local cell.
[0037] Referring to FIG. 5 which is a schematic DOA (direction of
arrival) diagram of a user equipment, an azimuth angle is an angle
between a projection of the direction of arrival on a horizontal
plane and a forward sighting direction of the antenna of the local
cell. An array in the figure illustrates an antenna array of a base
station.
[0038] The DOA information of a user equipment may be obtained in
one of the following three modes.
[0039] Mode 1: Obtain a direction of arrival parameter of a user
equipment within the service range of the local cell by estimation
according to an uplink channel quality measurement reference signal
reported by the user equipment within the service range of the
local cell.
[0040] Specifically, the base station of the local cell estimates,
by using a common DOA algorithm, an uplink SRS (Sounding reference
signal, uplink channel quality measurement reference signal)
reported by the user equipment within the service range of the
local cell (for example, reported by the user equipment proactively
and periodically or upon receiving signaling configured by the base
station), and thereby obtains the DOA parameter of the user
equipment within the range of the local cell, where the DOA
algorithm includes a Capon algorithm, or a Music (Multiple Signal
Classification, multiple signal classification) algorithm, and the
embodiment of the present invention sets no limit thereto.
[0041] The principle of a DOA algorithm is described briefly
herein. A signal receiving array of the antenna on the base station
of the local cell estimates an array response for a received uplink
SRS reported by a user equipment within the service range of the
local cell, and then performs relevance scanning between array
responses corresponding to different DOAs and the estimated array
response, and thereby obtains a DOA parameter with a greater
relevance with the SRS than a preset threshold. For example, when
the DOA parameter is downtilt information of a time-frequency
resource block on the antenna of the local cell with respect to
user equipments within the service range of the local cell, the
signal receiving array performs relevance scanning on the received
SRS between 0.degree. and 180.degree. in a vertical direction, and
uses the Capon algorithm to obtain that the signal received
strengths of the SRS between 10.degree. and 15.degree. are all
greater than a preset threshold; and therefore, it is considered
that the downtilt of the time-frequency resource block on the
antenna of the local cell with respect to the user equipment within
the service range of the local cell is between 10.degree. and
15.degree.. When the DOA parameter is azimuth angle information of
a time-frequency resource block of the antenna of the local cell
with respect to user equipments within the service range of the
local cell, the signal receiving array performs relevance scanning
on the received SRS between 0.degree. and 360.degree. in a
horizontal direction, and uses the Capon algorithm to obtain that
the signal received strengths of the SRS between 85.degree. and
95.degree. are all greater than a preset value; and therefore, it
is considered that the azimuth angle of the time-frequency resource
block on the antenna of the cell with respect to the user equipment
within the service range of the local cell is between 85.degree.
and 95.degree..
[0042] Mode 2: Transmit channel state information reference signals
of different direction of arrival parameters to a user equipment
within the service range of the local cell on pilot resource
elements within a time-frequency resource block on the antenna of
the local cell, and receive a direction of arrival parameter which
is returned by the user equipment within the service range of the
local cell and corresponding to a reference signal whose signal
received strength measured on the reference signal is greater than
a preset threshold.
[0043] Specifically, referring to FIG. 7, the base station of the
local cell transmits different CSI-RSs (Channel state information
reference signal, channel state information reference signal) to a
user equipment within the service range of the local cell, where
each CSI-RS uses a different DOA parameter. The user equipment
receives the CSI-RSs, measures signal received strengths of the
CSI-RSs, and returns, to the base station of the local cell, a DOA
parameter corresponding to a measured CSI-RS with a signal received
strength greater than a preset value. The base station of the local
cell receives the DOA parameter returned by the user equipment.
[0044] For example, when the DOA parameter is downtilt information
of a time-frequency resource block of the antenna of the local cell
with respect to user equipments within the service range of the
local cell and azimuth angle information of a time-frequency
resource block on the antenna of the local cell with respect to
user equipments within the service range of the local cell, the
base station of the local cell transmits CSI-RSs with respective
DOA parameters as 1.degree./6.degree., 3.degree./8.degree.,
5.degree./8.degree., and 6.degree./10.degree. to a user equipment
within the service range of the local cell. The user equipment
receives the CSI-RSs, and measures signal received strengths of the
CSI-RSs with the foregoing DOA parameters, which are, for example,
48%, 89%, 60%, and 40%, respectively. The user equipment may
return, to the base station of the local cell, the DOA parameters
3.degree./8.degree., and 5.degree./8.degree. corresponding to
CSI-RSs whose signal received strengths are greater than 50%.
[0045] In an actual operation, after measuring and obtaining the
DOA information, a user equipment may number a DOA with an index
number, and return the index number of the DOA to the base station
of the local cell. When the user equipment needs to return multiple
DOAs to the base station of the local cell, the user equipment may
report index numbers of the multiple DOAs to the base station of
the local cell by using a differential mode in the prior art. After
receiving the index numbers of the DOAs returned by the user
equipment, the base station of the local cell queries and obtains
DOA information according to a pre-stored mapping table between
index numbers and DOA information.
[0046] Mode 3: Transmit reference signals to a user equipment
within the service range of the local cell on pilot resource
elements within a time-frequency resource block on the antenna of
the local cell in a time division, frequency division, or code
division mode; receive a pre-code matrix of a channel state that is
obtained by the user equipment within the service range of the
local cell by estimation according to the reference signals; and
obtain a direction of arrival parameter of the user equipment
within the service range of the local cell by estimation according
to the pre-code matrix.
[0047] Specifically, referring to FIG. 7, the base station sends
reference signals to a user equipment within the service range of
the antenna of the local cell by using pilot resource elements
within a time-frequency resource block of the antenna of the local
cell in a time division, a frequency division, or a code division
mode. The user equipment receives the reference signals; obtains
channel states of channels corresponding to the pilot resource
elements by estimation according to the reference signals, to
obtain an N.sub.r.times.M dimensional channel matrix; and then,
according to the channel matrix, obtains a pre-code matrix which is
recommended for a transmit end to use, where N.sub.r is the number
of receive antennas on the user equipment, and M is the number of
pilot resource elements within the time-frequency resource block on
the antenna of the base station. The base station receives the
pre-code matrix returned by the user equipment, and decodes the
pre-code matrix to obtain a DOA parameter of the user
equipment.
[0048] Each square in FIG. 7 represents one pilot resource element
within a time-frequency resource block on the antenna of the local
cell.
[0049] An example with eight antenna array ports is briefly
described herein. Frequency division transmission mode: reference
signals are sent to a user equipment within the service range of
the antenna of the local cell by using pilot resource elements
within a time-frequency resource block on the antenna of the local
cell at different frequency points at one time point. Specifically,
in the mode illustrated by (a) in FIG. 7, a time-frequency resource
block has eight pilot resource elements, where each four pilot
resource elements occupy one frequency point (a shaded portion and
a non-shaded portion each represent one frequency point). At one
time point, reference signals of eight ports are sent to a user
equipment within the service range of the antenna of the local cell
at the two frequency points by using the eight pilot resource
elements, as shown in a first column and a second column in (a),
which presents a schematic diagram of transmitting reference
signals at two time points in a frequency division transmission
mode.
[0050] Time division transmission mode: at different time points of
one frequency point, reference signals are sent to a user equipment
within the service range of the antenna of the local cell by using
the pilot resource elements within a time-frequency resource block
on the antenna of the local cell. Specifically, in the mode
illustrated by (b) in FIG. 7, a time-frequency resource block has
eight pilot resource elements that are divided to two groups of
four at two frequency points. Pilot signals of eight array ports
are sent by using the eight pilot resource elements at two
different time points of one frequency point, as shown in a first
row and a second row in (b), which presents a schematic diagram of
transmitting reference signals at two different time points of one
frequency point.
[0051] Code division transmission mode: at one frequency point and
one time point, reference signals are sent to user equipments
within the service range of the antenna of the local cell by using
the pilot resource elements within a time-frequency resource block
on the antenna of the local cell. For example, as illustrated by
(c) in FIG. 7, the time-frequency resource block has eight pilot
resource elements, where eight array ports are divided into two
groups with each group having four ports. A pilot signal of an
n.sup.th port (where n=1, 2, 3, 4) in group 1 is multiplied by a
sequence (recorded as a) with a length of 2, and is placed in two
resource elements of the eight pilot resource elements (where the
two resource elements are expressed as an n.sup.th group of the
eight resource elements); a pilot signal at an n.sup.th port in
group 2 is multiplied by another sequence with a length of 2
(expressed as b, where a is orthogonal to b), and is placed in the
n.sup.th pilot resource element at the same place as the pilot
signal at the n.sup.th port in group 1 is placed, where a specific
mode is illustrated by (c) in FIG. 7.
[0052] In an actual operation, after obtaining a pre-code matrix, a
user equipment may number the pre-code matrix with an index number,
and return the index number of the pre-code matrix to the base
station. The base station searches a pre-stored mapping table
between index numbers and pre-code matrixes according to the
received index number of the pre-code matrix, and thereby obtains
the pre-code matrix. If the DOA parameter includes downtilt
information and azimuth angle information of a time-frequency
resource block of the antenna of the local cell with respect to
user equipments within the service range of the local cell, and the
downtilt information and azimuth angle information are separable,
the downtilt information and azimuth angle information are
quantized separately and represented by index numbers; then, the
index numbers are reported to the base station in a separate or
combined manner; and if the downtilt information and azimuth angle
information are inseparable, the pre-code matrix is quantized
uniformly and then a corresponding index number is reported to the
base station.
[0053] In addition, it should be noted that, when the method
described in mode 2 or mode 3 is used to obtain a DOA parameter of
a user equipment, the base station needs to configure a signaling
process in advance, to instruct the user equipment to get prepared
to measure CSI-RSs or pilots and return measurement information
within a required period.
[0054] For example, the downtilt information, obtained by using one
of the foregoing modes, of a time-frequency resource block on the
antenna of the local cell with respect to user equipments within
the service range of the local cell and signal received strengths
at the downtilts are shown in Table 1.
TABLE-US-00001 TABLE 1 Cell Downtilt information of a time-
frequency resource block of an antenna UE of a cell with respect to
a UE Signal received strength UE.sub.1 1.degree. 89% 3.degree. 70%
5.degree. 55% 8.degree. 43% 12.degree. 32% 15.degree. 12% UE.sub.2
2.degree. 25% 5.degree. 40% 7.degree. 60% 10.degree. 73% 13.degree.
80% 14.degree. 90% UE.sub.3 4.degree. 13% 5.degree. 35% 7.degree.
53% 9.degree. 88% 11.degree. 80% 15.degree. 65% . . . . . . . .
.
[0055] In the embodiment of the present invention, after a DOA
parameter of a user equipment is obtained, the downtilt or/and
azimuth angle of the antenna with respect to user equipments within
the service range may be processed according to the obtained DOA
parameter, so that the user equipment can better receive signals.
The embodiment of the present invention focuses on how to set,
according to the downtilt information in the obtained DOA
parameter, the downtilt of a time-frequency resource block on an
antenna with respect to a to-be-coordinated user equipment; how to
process the azimuth angle of an antenna with respect to a user
equipment within the service range according to the azimuth angle
information in the obtained DOA parameter is similar, and details
are not repeated herein.
[0056] Step 201-1-2: The base station of the local cell determines
optimal downtilt information of the time-frequency resource blocks
on the antenna of the local cell with respect to user equipments
within the service range of the local cell according to the
direction of arrival parameters.
[0057] Specifically, defining an optimal downtilt of a
time-frequency resource block on the antenna of the cell with
respect to a user equipment within the service range according to
the downtilt information of the time-frequency resource block on
the antenna of the local cell with respect to the user equipment
within the service range of the local cell in an obtained direction
of arrival parameter and the signal received strengths
corresponding to the downtilt information includes:
[0058] selecting, from the downtilt information of the
time-frequency resource block on the antenna of the local cell with
respect to user equipments within the service range of the local
cell in the obtained direction of arrival parameter, a downtilt
with respect to the user equipment that allows the user equipment
to receive a signal sent by the base station with a greatest signal
received strength, as an optimal downtilt of the time-frequency
resource block on the antenna with respect to user equipments
within the service range.
[0059] According to the contents of Table 1, the optimal downtilts
of a time-frequency resource block on the antenna of the local cell
with respect to user equipments within the service range are shown
in Table 2.
TABLE-US-00002 TABLE 2 Cell User equipment Optimal downtilt
UE.sub.1 1.degree. UE.sub.2 14.degree. UE.sub.3 9.degree. . . . . .
.
[0060] The base station of the local cell may obtain location
information of a user equipment within the service range of the
local cell by using one of the following two modes.
[0061] Mode 1: Obtain a direction of arrival parameter of the user
equipment within the service range of the local cell by estimation
according to an uplink channel quality measurement reference signal
reported by the user equipment within the service range of the
local cell, where the direction of arrival parameter at least
includes downtilt information of the time-frequency resource block
on the antenna of the local cell with respect to user equipments
within the service range of the cell; and obtain the location
information of the user equipment within the service range of the
local cell by calculation according to the direction of arrival
parameter.
[0062] Specifically, referring to FIG. 2, the location of the user
equipment may be obtained by calculation according to the downtilt
information of the time-frequency resource block on the antenna of
the local cell with respect to the user equipment, based on a
geometrical trigonometric function formula.
[0063] Mode 2: Receive location information which is obtained by
the user equipment within the service range of the local cell by
performing positioning according to a predetermined positioning
technology.
[0064] Specifically, after receiving, from the base station of the
local cell, an instruction for obtaining location information of
the user equipment, the user equipment returns, to the base station
of the local cell, the location information obtained by positioning
itself using a predetermined positioning technology, where the
predetermined positioning technology includes positioning
technologies such as GPS positioning, DOA positioning, or TDOA
positioning.
[0065] Obtaining, by the base station of the local cell, use
probabilities of downtilts on each time-frequency resource block on
the antenna of the cell includes: performing statistics, by the
base station of the local cell, on historical use of downtilts on
each time-frequency resource block on the antenna of the local cell
to obtain the use probabilities of downtilts on each time-frequency
resource block on the antenna of the local cell.
[0066] Obtaining, by the base station of the local cell, downtilts
not recommended by the local cell for time-frequency resource
blocks on an antenna of a neighboring cell specifically is:
receiving downtilt information, reported by at least one user
equipment served by the local cell, of a time-frequency resource
block on the antenna of the neighbor cell with respect to the
predetermined user equipment, and selecting the downtilts not
recommended by the local cell for time-frequency resource blocks on
the antenna of the neighboring cell from the downtilt information
of the time-frequency resource block on the antenna of the neighbor
cell with respect to the predetermined user equipment.
[0067] For example, regarding UE 1 served by the local cell within
an overlap coverage area of the local cell and the neighbor cell,
when a downtilt of a time-frequency resource block on the antenna
of the neighbor cell with respect to UE 1 is 2.degree., a received
strength of a signal received by UE 1 from the neighbor cell is
35%, which indicates that UE 1 receives strong interference from
the neighbor cell. As a result, the downtilts not recommended by
the local cell for a neighboring cell are downtilts smaller than
2.degree..
[0068] Step 201-2: The base station of the local cell obtains the
downtilt coordination information of the neighbor cell, where the
downtilt coordination information of the neighbor cell includes one
or more of: optimal downtilt information of time-frequency resource
blocks on an antenna of a neighbor cell with respect to user
equipments within a service range of a neighbor cell, location
information of user equipments within the service range of a
neighbor cell, location information of a base station of a neighbor
cell, use probabilities of downtilts on each time-frequency
resource block on the antenna of a neighbor cell, probabilities
that each time-frequency resource block of the base station of a
neighbor cell is assigned to different user equipments, and
downtilts not recommended for time-frequency resource blocks on an
antenna of a neighboring cell.
[0069] Specifically, the base station of the local cell receives
the downtilt coordination information of the neighbor cell sent by
the base station of the neighbor cell, where the downtilt
coordination information of the neighbor cell is obtained by the
base station of the neighbor cell by using the method described in
step 201-1, and details are not repeated herein.
[0070] In specific implementation, over a predetermined interface,
the base station of the local cell receives the downtilt
coordination information of the neighbor cell sent by the base
station of the neighbor cell, and optionally, may also send the
obtained downtilt coordination information of the local cell to the
base station of the neighbor cell, where the predetermined
interface may be an X2 interface between two neighboring base
stations.
[0071] In addition, it should be noted that, when the downtilt
coordination information of the neighbor cell obtained by the base
station of the local cell includes downtilts not recommended by the
neighbor cell for time-frequency resource blocks on an antenna of a
neighboring cell, the following method may be used for
implementation:
[0072] obtaining a direction of arrival parameter of a user
equipment within the service range of the neighbor cell, where the
direction of arrival parameter at least includes downtilt
information of a time-frequency resource block on the antenna of
the local cell with respect to the user equipment within the
service range of the neighbor cell, and determining, according to
the direction of arrival parameter, downtilts not recommended by
the neighbor cell for time-frequency resource blocks on an antenna
of a neighboring cell.
[0073] Obtaining the direction of arrival parameter of a user
equipment within the service range of the neighbor cell
includes:
[0074] sending channel state information reference signals of
different direction of arrival parameters to the user equipment
within the service range of the neighbor cell on pilot resource
elements within a time-frequency resource block on the antenna of
the local cell, and receiving a direction of arrival parameter
returned by the user equipment within the service range of the
neighbor cell and corresponding to a reference signal whose signal
received strength obtained by measurement on the reference signal
is greater than a preset threshold; where, in actual
implementation, the user equipment within the service range of the
neighbor cell may obtain information related to the reference
signals of the local cell from the base station of the local cell
in advance, where the direction of arrival parameter returned by
the user equipment after measurement may be sent directly to the
base station of the local cell, or may be sent to the base station
of the neighbor cell which serves the user equipment, and then
forwarded by the base station of the neighbor cell to the base
station of the local cell over an interface with the base station
of the local cell; or
[0075] sending reference signals to a user equipment within the
service range of the neighbor cell on pilot resource elements
within a time-frequency resource block on the antenna of the local
cell in a time division, frequency division, or code division mode,
receiving a pre-code matrix of a channel state obtained by the user
equipment within the service range of the neighbor cell by
estimation according to the reference signals, and obtaining, by
estimation according to the pre-code matrix, the direction of
arrival parameter of the user equipment within the service range of
the neighbor cell; where, in actual implementation, the user
equipment within the service range of the neighbor cell may obtain
information related to the reference signals of the local cell from
the base station of the local cell in advance, and the pre-code
matrix of the channel state returned by the user equipment after
measurement may be sent directly to the base station of the local
cell, or may be sent to the base station of the neighbor cell which
serves the user equipment, and then forwarded by the base station
of the neighbor cell to the base station of the local cell over an
interface with the base station of the local cell; or
[0076] obtaining the direction of arrival parameter of the user
equipment within the service range of the antenna of the neighbor
cell by estimation according to an uplink channel quality
measurement reference signal reported by the user equipment within
the service range of the antenna of the neighbor cell; where, in
actual implementation, before measuring the reference signal, the
base station of the local cell may obtain, according to information
notified by the base station of the neighbor cell explicitly or
implicitly, a sequence used by the uplink channel quality
measurement reference signal reported by the user equipment within
the service range of the antenna of the neighbor cell.
[0077] For detailed description of the foregoing method, reference
may be made to the related description in step 201-1-1, and details
are not repeated herein.
[0078] Optionally, step 202: the base station of the local cell
assigns, according to the downtilt coordination information of the
local cell, a time-frequency resource block on the antenna of the
local cell to the to-be-coordinated user equipment.
[0079] Specifically, the time-frequency resource block is assigned
on the antenna of the local cell to the to-be-coordinated user
equipment by using the following three modes.
[0080] Mode 1: Classify user equipments within the service range of
the local cell, and assign a time-frequency resource block on the
antenna of the local cell to the to-be-coordinated user equipment
according to the classification information of user equipments
within the service range of the local cell based on an FFR
(Fractional Frequency Reuse, fractional frequency reuse) scheduling
principle.
[0081] This mode specifically includes the following steps.
[0082] Step 202-1A: Classify, by location, user equipments within
the service range of the local cell to obtain location
classification information of user equipments within the service
range of the cell.
[0083] User equipments within the service range of the local cell
may be classified by location by using one of the following
modes.
[0084] Mode A: Classify user equipments within the service range of
the local cell based on a pre-defined assignment rule according to
the optimal downtilt information, in the downtilt coordination
information of the local cell, of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell.
[0085] Specifically, a user equipment whose user equipment optimal
downtilt falls within a first predefined range is regarded as a
user equipment of a first category; a user equipment whose user
equipment optimal downtilt falls within a second predefined range
is regarded as a user equipment of a second category, and a user
equipment whose user equipment optimal downtilt falls within a
third predefined range is regarded as a user equipment of a third
category, and so on. For example, a user equipment whose user
equipment optimal downtilt falls within a range of 1.degree. to
5.degree. is regarded as a user equipment of a first category,
which is referred to as a cell-edge user equipment; a user
equipment whose user equipment optimal downtilt falls within a
range of 6.degree. to 10.degree. is regarded as a user equipment of
a second category, which is referred to as a cell-outer user
equipment; and a user equipment whose user equipment optimal
downtilt falls within a range of 11.degree. to 15.degree. is
regarded as a user equipment of a third category, which is referred
to as a cell-center user equipment.
[0086] User equipments after the classification may be represented
by using a set
UE.sub.x={ue.sub.i|foe(ue.sub.i).epsilon..THETA..sub.x}, where x
represents a range subscript ("center", "outer", or "edge") of a
downtilt of a time-frequency resource block on an antenna with
respect to the user equipment, and "center", "outer", and "edge"
respectively represent the center area, outer area, and edge area
of the cell; foe(ue.sub.i) is an optimal downtilt of ue.sub.i;
.THETA..sub.x is an angle range corresponding to the x area. For
example, in the above example,
.THETA..sub.edge={.theta.|1.degree..ltoreq..theta..ltoreq.5.degr-
ee.},
.THETA..sub.outer={.theta.|6.degree..ltoreq..theta..ltoreq.10.degree-
.}, and
.THETA..sub.enter={.theta.|11.degree..ltoreq..theta..ltoreq.15.deg-
ree.}.
[0087] For example, according to Table 2, UE.sub.1 belongs to
UE.sub.edge, UE.sub.3 belongs to UE.sub.outer, and UE.sub.2 belongs
to UE.sub.center.
[0088] Mode B: Classify user equipments within the service range of
the local cell according to the location information, in the
downtilt coordination information of the local cell, of user
equipments within the service range of the local cell.
[0089] Step 202-2A: Select, according to the location
classification information of user equipments within the service
range of the local cell, a category of user equipments of great
coordination urgency within the service range of the local cell,
which are expressed as a set UE.sub.edge,l.
[0090] As shown in FIG. 2, generally, when a vertical beam points
to UEs in the cell edge area, the interference on a neighbor cell
is greater than when the vertical beam points to UEs in the cell
outer area or cell center area. That is, UEs belonging to
UE.sub.edge are of great coordination urgency. It is assumed that
there are two neighboring cells. UEs belonging to UE.sub.edge and
selected from downtilt coordination information of cell 1 include
UE.sub.1, UE.sub.5, and UE.sub.7, which are expressed as
UE.sub.edge,1; and UEs belonging to UE.sub.edge and selected from
downtilt coordination information of cell 2 include UE.sub.10,
UE.sub.9, and UE.sub.60, which are expressed as UE.sub.edge,2.
[0091] Step 202-3A: Several neighboring cells identify
non-overlapping frequency bands F.sub.1, . . . , F.sub.L. For
example, cell 1 corresponds to F.sub.1, cell 2 corresponds to
F.sub.2, . . . , and cell L corresponds to F.sub.L, where F.sub.l
refers to a coordination frequency band of cell l.
[0092] Step 202-4A: Allocate UE.sub.edge,l of the neighboring cells
to different coordination frequency bands.
[0093] For example, cell 1 allocates UE.sub.edge,1={UE.sub.1,
UE.sub.5, UE.sub.7} to the frequency band F.sub.1, and cell 2
allocates UE.sub.edge,2={UE.sub.10, UE.sub.9, UE.sub.60} to the
frequency band F.sub.2.
[0094] Step 202-5A: Coordinate and schedule time-frequency
resources for user equipments on the assigned frequency bands
according to PF (Proportional Fair, proportional fair) priorities.
Specifically, a time-frequency resource is assigned to a user
equipment with a highest PF priority on the time-frequency
resource.
[0095] For example, cell 1 schedules user equipments within
UE.sub.edge,1 on F.sub.1 according to PF priorities, where UE.sub.1
has the highest PF priority on the time-frequency resource
RU.sub.1, and assigns RU.sub.1 to UE.sub.1; and schedules UEs
served by cell 1 other than UEs in UE.sub.edge,1 on F.sub.2. Cell 2
schedules UEs within UE.sub.edge,2 on F.sub.2 according to PF
priorities, and schedules user equipments served by cell 2 other
than user equipments in UE.sub.edge,2 on F.sub.1.
[0096] In this step, UEs that may substantially interfere with each
other in the two neighboring cells are allocated onto two different
frequency bands, which prevents the neighbor cell from assigning
the same time-frequency resource to user equipments that
substantially interfere with the neighbor cell, thereby reducing
difficulty in subsequent downtilt coordination.
[0097] Mode 2: Classify user equipments within the service range of
the local cell, and assign a time-frequency resource block on the
antenna of the local cell to the to-be-coordinated user equipment
according to the classification information of user equipments
within the service range of the local cell based on an SFR (Soft
Frequency Reuse, soft frequency reuse) scheduling principle.
[0098] This mode specifically includes the following steps.
[0099] Step 202-1B: Classify, by location, user equipments within
the service range of the local cell to obtain location
classification information of user equipments within the service
range of the cell.
[0100] For a specific implementation process of this step,
reference may be made to description of step 202-1A, and details
are not repeated herein.
[0101] Step 202-2B: Select, according to the location
classification information of user equipments within the service
range of the local cell, a category of user equipments of great
coordination urgency within the service range of the local cell,
which are expressed as a set UE.sub.edge,l.
[0102] This step is specifically the same as step 202-2A, and
details are not repeated herein.
[0103] Step 202-3B: Several neighboring cells identify
non-overlapping frequency bands F.sub.1, . . . , F.sub.L. For
example, cell 1 corresponds to F.sub.1, cell 2 corresponds to
F.sub.2, . . . , and cell L corresponds to F.sub.L, where F.sub.l
refers to a coordination frequency band of cell l.
[0104] Step 202-4B: User equipments in UE.sub.edge,l of cell l have
high priorities on a identified coordination frequency band, and
other user equipments served by cell l have low priorities on the
coordination frequency band; and user equipments in UE.sub.edge,l
of cell l have low priorities on a non-coordination frequency band,
and other user equipments served by cell l have high priorities on
the non-coordination frequency band.
[0105] Step 202-5B: Coordinate and assign time-frequency resources
for user equipments on the assigned frequency bands according to PF
(Proportional fair, proportional fair) priorities, and adjust the
priorities of the user equipments.
[0106] Specifically, when assigning resource blocks on F.sub.l,
cell l determines whether a user equipment belongs to
UE.sub.edge,l, and if yes, the PF priority of the user equipment is
adjusted to:
PF=(1+a)PF.sub.origion
[0107] and otherwise, to
PF=(1-b)PF.sub.origion
[0108] where PF.sub.origion is a PF obtained by calculation
according to a CQI (Channel quality indicator, channel quality
indicator) and historical rates before the adjustment, a>1 and
0<b<1. Similarly, when assigning resource blocks on frequency
bands other than F.sub.l, cell l determines whether a user
equipment belongs to UE.sub.edge,l; if not, the PF priority of the
user equipment is adjusted to
PF=(1+c)PF.sub.origion
[0109] and otherwise, to
PF=(1-d)PF.sub.origion
[0110] where c>1 and 0<d<1.
[0111] Step 202-6B: Assign time-frequency resources to user
equipments according to the adjusted priorities, and specifically,
a time-frequency resource is assigned to a user equipment with a
highest PF priority on the time-frequency resource.
[0112] Mode 3: Classify user equipments within the service range of
the local cell, and assign a time-frequency resource block on the
antenna of the local cell to the to-be-coordinated user equipment
based on a self-defined dynamic scheduling principle according to
the classification information of user equipments within the
service range of the local cell and the use probabilities, in the
coordination information of the neighbor cell, of downtilts on each
time-frequency resource block on the antenna of the neighbor
cell.
[0113] For a method for classifying user equipments within the
service range of the local cell, reference may be made to the
description of step 202-1A and details are not repeated herein.
[0114] The coordination and scheduling according to a self-defined
dynamic scheduling principle specifically includes the
following:
[0115] When assigning a k.sup.th resource block to a user
equipment, the local cell makes reference to the downtilt
coordination information of the neighbor cell, and adjusts a
priority of the user equipment according to the information. For
example, the local cell determines a coordination rule according to
the downtilts not recommended for use or use probabilities of
downtilts in the downtilt coordination information of the neighbor
cell. A preferred rule is that, on the same resource block:
[0116] 1) it is avoided that user equipments within the service
range of the antenna of the neighbor cell belong to UE.sub.edge
sets of their respective cells;
[0117] 2) if a downtilt .theta..sub.2 with respect to user
equipments within the service range of the antenna of the neighbor
cell on the resource block belongs to a set .THETA..sub.edge, the
local cell assigns the resource block preferentially to a user
equipment in UE.sub.center, and secondly to a user equipment in
UE.sub.outer;
[0118] 3) if a downtilt .theta..sub.2 with respect to user
equipments within the service range of the antenna of the neighbor
cell on the resource block belongs to a set .THETA..sub.outer, the
local cell assigns the resource block preferentially to a user
equipment in UE.sub.outer, secondly to a user equipment in
UE.sub.center, and thirdly to a user equipment in UE.sub.edge;
and
[0119] 4) if a downtilt .theta..sub.2 with respect to user
equipments within the service range of the antenna of the neighbor
cell on the resource block belongs to a set .THETA..sub.center, the
local cell assigns the resource block preferentially to a user
equipment in UE.sub.outer, secondly to a user equipment in
UE.sub.edge, and thirdly to a user equipment in UE.sub.center.
[0120] The above describes merely one self-defined dynamic
scheduling principle provided by the embodiment of the present
invention. Any modification, equivalent replacement, and
improvement made to the self-defined dynamic scheduling principle
within the spirit and principle of the present invention shall fall
within the protection range of the present invention.
[0121] It should be noted that step 202 is an optional step. This
step ensures, as much as possible through resource assignment, that
vertical beams do not collide when downtilts of neighboring cells
with respect to user equipments on the same resource block equal
the optimal downtilts with respect to the user equipment, thereby
reducing difficulty in subsequent downtilt coordination.
[0122] Step 203: Set, according to the downtilt coordination
information of the local cell and the downtilt coordination
information of the neighbor cell, a downtilt of a time-frequency
resource block on the antenna of the local cell with respect to the
to-be-coordinated user equipment.
[0123] This step specifically includes the following
operations.
[0124] Step 203-1: Determine a range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell according to the downtilt coordination information of
the local cell and the downtilt coordination information of the
neighbor cell.
[0125] Determining a range of usable downtilts for time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell
according to the downtilt coordination information of the local
cell and the downtilt coordination information of the neighbor cell
may include:
[0126] determining a range of optimal downtilts for time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell
according to the optimal downtilt information, in the downtilt
coordination information of the local cell, of time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell; and
using a range of downtilts within the range of optimal downtilts,
excluding downtilts which are in the downtilt coordination
information of the neighbor cell and are not recommended for a
neighboring cell, as the range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell.
[0127] For example, according to Table 2, the optimal downtilt of
the user equipment UE1 within the service range of the local cell
is 1.degree., the optimal downtilt of UE2 is 14.degree., and the
optimal downtilt of UE3 is 9.degree.. Therefore, the range of
optimal downtilts of time-frequency resource blocks on the antenna
of the local cell with respect to user equipments within the
service range of the local cell may be set to 1.degree. to
14.degree.. In the downtilt coordination information of the
neighbor cell received from the base station of the neighbor cell,
downtilts not recommended for a neighboring cell on a
time-frequency resource block are smaller than 4.degree..
Therefore, the range of usable downtilts of the time-frequency
resource block on the antenna of the local cell with respect to
user equipments within the service range of the local cell is
4.degree. to 14.degree..
[0128] Alternatively, determining a range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell according to the downtilt coordination information of
the local cell and the downtilt coordination information of the
neighbor cell may include:
[0129] determining a range of optimal downtilts for time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell
according to optimal downtilt information, in the downtilt
coordination information of the local cell, of time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell;
obtaining a set consisting of neighbor cell downtilts whose use
probabilities exceed a first threshold according to use
probabilities, in the downtilt coordination information of the
neighbor cell, of downtilts of the antenna of the neighbor cell on
the time-frequency resource blocks; according to location
information of the base station of the neighbor cell and location
information of the base station of the local cell, calculating a
downtilt set B of the antenna of the local cell with respect to
geographical locations corresponding to the set consisting of the
neighbor cell downtilts; and using a range of downtilts within the
range of the optimal downtilts, excluding downtilts in the set B,
as the range of usable downtilts for time-frequency resource blocks
on the antenna of the local cell with respect to user equipments
within the service range of the local cell; or
[0130] determining a range of optimal downtilts for time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell
according to optimal downtilt information, in the downtilt
coordination information of the local cell, of time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell;
according to location information, in the downtilt coordination
information of the neighbor cell, of UEs within the service range
of the neighbor cell and location information of the base station
of the local cell, calculating a downtilt set C of the antenna of
the local cell with respect to the location information of the UEs
of the neighbor cell; or according to optimal downtilt information
of time-frequency resource blocks on the antenna of the neighbor
cell with respect to user equipments within the service range of
the neighbor cell and the location information of the base station
of the neighbor cell, calculating geographical locations
corresponding to the optimal downtilts, and according to the
geographical locations corresponding to the optimal downtilts and
the location information of the base station of the local cell,
calculating a downtilt set C of the antenna of the local cell with
respect to the geographical locations corresponding to the optimal
downtilts; and using a range of downtilts within the range of
optimal downtilts, excluding downtilts in the set C, as the range
of usable downtilts for time-frequency resource blocks on the
antenna of the local cell with respect to user equipments within
the service range of the local cell; or
[0131] determining a range of optimal downtilts for time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell
according to optimal downtilt information, in the downtilt
coordination information of the local cell, of time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell;
according to probabilities, in the downtilt coordination
information of the neighbor cell, that each time-frequency resource
block of the base station of the neighbor cell is assigned to
different user equipments, searching for a user equipment whose
probability of being assigned with a time-frequency resource block
of the neighbor cell is greater than a second threshold, and
according to location information of the found UE and the location
information of the base station of the local cell, calculating a
downtilt set D of the antenna of the local cell with respect to the
location information of the found UE; or according to optimal
downtilt information of time-frequency resource blocks on the
antenna of the neighbor cell with respect to the found UE and the
location information of the base station of the neighbor cell,
calculating geographical locations corresponding to the optimal
downtilts, and according to the geographical locations
corresponding to the optimal downtilts and the location information
of the base station of the local cell, calculating a downtilt set D
of the antenna of the local cell with respect to the geographical
locations corresponding to the optimal downtilts; and using a range
of downtilts within the range of optimal downtilts, excluding
downtilts in the set D, as the range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell.
[0132] The downtilt set B, C, or D may be downtilts not recommended
by the neighbor cell for time-frequency resource blocks on an
antenna of a neighboring cell to use, and may be obtained by the
base station of the neighbor cell and then sent to the base station
of the local cell as downtilt coordination information, or may be
obtained by the base station of the local cell according to the
foregoing methods.
[0133] FIG. 8 may be referenced to for a method for calculating the
downtilt set B, C, or
[0134] D, where the geographical location that a vertical main beam
of the neighbor cell points to, that is, the geographical location
corresponding to the downtilt set of the neighbor cell, may be
obtained according to a geometrical relationship by using the
downtilts in the downtilt set of the neighbor cell and the location
information of the base station of the neighbor cell. The downtilt
set (for example, B, C, or D) of the antenna of the local cell may
be obtained according to a geometrical relationship by using the
location information of the base station of the local cell and the
geographical location corresponding to the downtilt set of the
neighbor cell. Of course, the downtilt set (for example, B, C, or
D) of the antenna of the local cell may also be obtained according
to the geometrical relationship directly by using the location
information of UEs served by the neighbor cell and the location
information of the base station of the local cell.
[0135] Alternatively, determining a range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell according to the downtilt coordination information of
the local cell and the downtilt coordination information of the
neighbor cell may include:
[0136] obtaining a distance between the base station of the local
cell and the base station of the neighbor cell by calculation
according to the location information of the base station of the
neighbor cell in the neighbor cell coordination information and the
location information of the base station of the local cell in the
local cell coordination information, and obtaining the range of
usable downtilts for time-frequency resource blocks on the antenna
of the local cell with respect to user equipments within the
service range of the local cell by calculation according to the
distance and a vertical main beam width of the antenna of the local
cell based on a geometrical relationship.
[0137] An example of obtaining a range of usable downtilts based on
a geometrical relationship is as follows:
.THETA..sub.valid,x=[.theta..sub.OP-BW/a,.beta.]
[0138] where .THETA..sub.valid,x is the range of usable downtilts
for time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell; .theta..sub.OP=arctan(b.times.H/D)-BW/c, where BW is
the vertical main beam width of the antenna of the local cell, H is
a difference between the height of the base station and an average
height of user equipments, and D is the distance between the base
station of the local cell and the base station of the neighbor
cell; and a, b, c, and .beta. are positive real numbers and
preferably, a is 8, b is 2, c is 2, and .beta. is 90.degree..
[0139] Persons of ordinary skill in the art may obtain information
such as the vertical main beam width of the antenna of the local
cell, the height of the base station, and the average height of
user equipments by using basic technical knowledge and common
technical approaches.
[0140] Step 203-2: Set the downtilt of a time-frequency resource
block on the antenna of the local cell with respect to the
to-be-coordinated user equipment according to the range of usable
downtilts based on a preset rule.
[0141] Specifically, in this step, the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment may be set in the
following four modes.
[0142] Mode 1: Obtain optimal downtilt information of the
to-be-coordinated user equipment from the optimal downtilt
information, in the local cell coordination information, of
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell; traverse all usable downtilts in the range of usable
downtilts to find a usable downtilt that is closest to the optimal
downtilt of the to-be-coordinated user equipment; and set the
downtilt of the time-frequency resource block on the antenna of the
local cell with respect to the to-be-coordinated user equipment to
the usable downtilt that is closest to the optimal downtilt of the
to-be-coordinated user equipment.
[0143] Mode 2: Traverse all usable downtilts in the range of usable
downtilts to find a usable downtilt that allows the
to-be-coordinated user equipment to have a greatest signal received
power, and set the downtilt of the time-frequency resource block on
the antenna of the local cell with respect to the to-be-coordinated
user equipment to the usable downtilt that allows the
to-be-coordinated user equipment to have the greatest signal
received power.
[0144] An equation for calculating the signal received power of the
to-be-coordinated user equipment is:
P ( .theta. , .theta. i ) = 1 N n = - N / 2 N / 2 G ( .theta. ,
.theta. i + n .DELTA. .theta. ) ; ##EQU00001##
where N is a predefined number of paths, where the number of paths
is a total number of channels between the antenna of the local cell
and user equipments within the service range of the local cell;
n.DELTA..theta. is an estimated vertical extension angle (which may
be obtained by estimation according to the obtained DOA parameter
by using a common estimation algorithm in the prior art) of the
antenna of the cell; and G(.theta., .theta..sub.i+n.DELTA..theta.)
is an antenna gain when the downtilt set on the antenna for the
to-be-coordinated user equipment is .theta. but the
to-be-coordinated user equipment is located in
.theta..sub.2+n.DELTA..theta..
[0145] Persons of ordinary skill in the art may obtain the antenna
gain in the foregoing equation by calculation according to basic
common technical knowledge.
[0146] For example, the range of usable downtilts is 13.degree. to
90.degree., while an optimal downtilt of a time-frequency resource
block on the antenna with respect to the to-be-coordinated user
equipment is 10.degree.. If the downtilt on the time-frequency
resource block with respect to the to-be-coordinated user equipment
is set to 10.degree., the to-be-coordinated user equipment has the
greatest signal received power. However, considering that the
interference on the neighbor cell increases when the downtilt is
smaller than 13.degree., according to the method described in mode
1, downtilts from 13.degree. to 90.degree. are traversed to find a
usable downtilt that is closest to the optimal downtilt of the
time-frequency resource block on the antenna with respect to the
to-be-coordinated user equipment, that is, 13.degree.. Therefore,
the downtilt of the time-frequency resource block of the antenna of
the local cell with respect to the to-be-coordinated user equipment
should be set to 13.degree.. In this case, although the user
equipment does not have the greatest signal received power, the
interference on the neighbor cell is reduced, which helps to
improve the SINR experience of a whole system.
[0147] Mode 3: Traverse all usable downtilts in the range of usable
downtilts to find a usable downtilt that allows a greatest
signal-to-leakage-and-noise ratio, and set the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment to the usable
downtilt that allows the greatest signal-to-leakage-and-noise ratio
(Signal-to-Leakage-and-Noise Ratio, SLNR).
[0148] The SLNR on the time-frequency resource block of the antenna
of the local cell may be obtained by calculation according to the
following formula:
P t G ( .theta. 0 , .theta. target - UE ) PL UE 1 - cell 1 k = 1 k
.alpha. k P T G ( .theta. 0 , .theta. UEk ) PL UEk - cell 1
##EQU00002##
[0149] The SLNR may also be obtained by calculation by using other
methods in the prior art, and details are not described herein.
[0150] In the formula, P.sub.T is a transmit power when the
to-be-coordinated user equipment transmits a signal (which may be
obtained by performing power measurement);
[0151] .theta..sub.0 is a downtilt of the time-frequency resource
block of the antenna of the local cell with respect to the
to-be-coordinated user equipment;
[0152] .theta..sub.target-UE is the optimal downtilt of the
to-be-coordinated user equipment (which may be obtained from the
optimal downtilt coordination information, in the downtilt
coordination information of the local cell, of the time-frequency
resource block of the antenna of the local cell with respect to the
user equipment);
[0153] G(.theta..sub.0, .theta..sub.target-UE) is an antenna gain
when the downtilt of the time-frequency resource on the antenna of
the local cell with respect to the to-be-coordinated user equipment
is set to .theta..sub.0 but the to-be-coordinated user equipment is
located in .theta..sub.target-user equipment (which may be obtained
by calculation according to an existing method for calculating the
antenna gain);
[0154] PL.sub.user equipment 1-cell1 is a path loss from the
to-be-coordinated user equipment to the local cell (which may be
obtained by estimation according to the DOA parameter using an
estimation algorithm in the prior art or by measurement using an
RSRP (Reference Signal Received Power, reference signal received
power));
[0155] .alpha..sub.k is a probability, given by the neighbor cell,
that the time-frequency resource block is assigned to a k.sup.th
user equipment (which may be obtained by performing statistics by
the base station of the neighbor cell and sent to the base station
of the local cell over an X2 interface); and
[0156] PL.sub.UEk-cell is a path loss from the k.sup.th device
within the service range of the neighbor cell to the local cell
(which may be obtained by measurement using an RSRP (Reference
Signal Received Power, reference signal received power)).
[0157] Mode 4: Traverse all usable downtilts in the range of usable
downtilts to find a usable downtilt that allows a greatest sum of
signal-to-interference-plus-noise ratios, and set the downtilt of
the time-frequency resource block on the antenna of the local cell
with respect to the to-be-coordinated user equipment as the usable
downtilt that allows the greatest sum of
signal-to-interference-plus-noise ratios.
[0158] Specifically, the sum of signal-to-interference-plus-noise
ratios on the time-frequency resource block of the antenna of the
local cell may be obtained by calculation according to the
following formula:
P T G ( .theta. 1 , .theta. UE 1 - cell 1 ) PL UE 1 - cell 1 P T G
( .theta. 2 , .theta. UE 1 - cell 2 ) PL UE 1 - cell 2 + P T G (
.theta. 2 , .theta. UE 2 - cell 2 ) PL UE 2 - cell 2 P T G (
.theta. 2 , .theta. UE 2 - cell 1 ) PL UE 2 - cell 1
##EQU00003##
[0159] The sum of signal-to-interference-plus-noise ratios may also
be obtained by calculation by using other methods in the prior art,
and details are not described herein.
[0160] This formula presents how to calculate a sum of
signal-to-interference-plus-noise ratios of two neighboring cells.
The method for calculating a sum of
signal-to-interference-plus-noise ratios of several neighboring
cells is similar.
[0161] In the formula, P.sub.T is a transmit power when the
to-be-coordinated user equipment transmits a signal (which may be
obtained by performing power measurement);
[0162] .theta..sub.1 is a downtilt of a time-frequency resource
block of the antenna of the local cell with respect to the
to-be-coordinated user equipment within the service range of the
local cell;
[0163] .theta..sub.2 a downtilt of the time-frequency resource
block on the antenna of the neighbor cell with respect to the
to-be-coordinated user equipment within the service range of the
neighbor cell, which may be obtained according to the probabilities
that each time-frequency resource block on the base station of the
neighbor cell is assigned to different user equipments and the
optimal downtilt information of the time-frequency resource block
on the antenna of the neighbor cell with respect to user equipments
within the service range of the neighbor cell;
[0164] G(.theta..sub.1, .theta..sub.UE1-Cell1) is an antenna gain
when a downtilt of the time-frequency resource on the antenna of
the local cell with respect to the to-be-coordinated user equipment
within the service range of the local cell is set to .theta..sub.1,
but the to-be-coordinated user equipment within the service range
of the local cell is located in .theta..sub.UE1-Cell1 relative to
the local cell (which may be obtained by calculation according to
an existing method for calculating an antenna gain);
[0165] PL.sub.UE1-cell1 is a path loss from the to-be-coordinated
user equipment within the service range of the local cell to the
local cell (which may be obtained by estimation according to the
DOA parameter of the local cell using an estimation algorithm in
the prior art or by measurement using an RSRP (Reference Signal
Received Power, reference signal received power));
[0166] G(.theta..sub.2, .theta..sub.UE2-Cell2) is an antenna gain
when a downtilt of the time-frequency resource of the antenna of
the neighbor cell with respect to the to-be-coordinated user
equipment within the service range of the neighbor cell is set to
.theta..sub.2, but the to-be-coordinated user equipment within the
service range of the neighbor cell is located in
.theta..sub.UE2-Cell2 relative to the neighbor cell (which may be
obtained by calculation according to an existing method for
calculating an antenna gain);
[0167] PL.sub.UE2-cell2 is a path loss from the to-be-coordinated
user equipment within the service range of the neighbor cell to the
neighbor cell (which may be obtained by estimation according to the
DOA parameter of the neighbor cell or by measurement using an RSRP
(Reference Signal Received Power, reference signal received
power));
[0168] G(.theta..sub.2, .theta..sub.UE1-Cell2) is an antenna gain
when a downtilt of the time-frequency resource of the antenna of
the neighbor cell with respect to the to-be-coordinated user
equipment within the service range of the local cell is set to
.theta..sub.2, but the to-be-coordinated user equipment within the
service range of the local cell is located in .theta..sub.UE1-Cell2
relative to the local cell (which may be obtained by calculation
according to an existing method for calculating an antenna
gain);
[0169] PL.sub.UE1-cell2 is a path loss from the to-be-coordinated
user equipment within the service range of the local cell to the
neighbor cell (which may be obtained by estimation according to the
DOA parameter of the local cell or by measurement using an RSRP
(Reference Signal Received Power, reference signal received
power));
[0170] G(.theta..sub.1, .theta..sub.UE2-Cell1) is an antenna gain
when a downtilt of the time-frequency resource block of the antenna
of the local cell with respect to the to-be-coordinated user
equipment within the service range of the neighbor cell is set to
.theta..sub.1, but the to-be-coordinated user equipment within the
service range of the neighbor cell is located in
.theta..sub.UE2-Cell1 relative to the neighbor cell (which may be
obtained by calculation according to an existing method for
calculating an antenna gain); and
[0171] PL.sub.UE2-cell1 is a path loss from the to-be-coordinated
user equipment within the service range of the neighbor cell to the
local cell (which may be obtained by estimation according to the
DOA parameter of the neighbor cell). It should be noted that user
equipments within the service range of the local cell or user
equipments within the service range of the neighbor cell refer to:
all or part of user equipments within the service range of the
local cell, or all or part user equipments within the service range
of the neighbor cell, where the part of user equipments refer to
user equipments that require coordination, moving user equipments,
or user equipments defined according to other rules within the
service range of the local cell or within the service range of the
neighbor cell.
[0172] By implementing the technical solutions of obtaining
downtilt coordination information of a local cell and downtilt
coordination information of a neighbor cell, and then setting,
according to the downtilt coordination information of the local
cell and the downtilt coordination information of the neighbor
cell, a downtilt of a time-frequency resource block on an antenna
of the local cell with respect to a to-be-coordinated user
equipment, the downtilt coordination information of the local cell
and that of the neighbor cell are referenced to for setting the
downtilt of the time-frequency resource block on the antenna of the
local cell with respect to the to-be-coordinated user equipment,
which avoids interference on user equipments within a service range
of the neighbor cell while ensuring signal received powers and SINR
experience for user equipments within a service range of the local
cell.
[0173] Referring to FIG. 9, an embodiment of the present invention
provides an apparatus for downtilt coordination. The apparatus
specifically corresponds to a base station or network node in the
method embodiments, and no specific limit is made thereto by the
embodiment of the present invention. The apparatus includes an
obtaining module 301 and a setting module 302.
[0174] The obtaining module 301 is configured to obtain downtilt
coordination information of a local cell and downtilt coordination
information of a neighbor cell, where either downtilt coordination
information of the downtilt coordination information of the local
cell and the downtilt coordination information of the neighbor cell
includes one or more of: optimal downtilt information of
time-frequency resource blocks on an antenna of a cell with respect
to user equipments within a service range of the cell, location
information of user equipments within the service range of the
cell, location information of a base station of the cell, use
probabilities of downtilts on each time-frequency resource block on
the antenna of the cell, probabilities that each time-frequency
resource block of the base station of the cell is assigned to
different user equipments, and downtilts not recommended for
time-frequency resource blocks on an antenna of a neighboring
cell.
[0175] The setting module 302 is configured to set, according to
the downtilt coordination information of the local cell and the
downtilt coordination information of the neighbor cell obtained by
the obtaining module 301, a downtilt of a time-frequency resource
block on the antenna of the local cell with respect to a
to-be-coordinated user equipment.
[0176] Specific functions of the foregoing modules are described in
detail as follows.
[0177] Specifically, the obtaining module 301 includes:
[0178] a first obtaining unit, configured to obtain a direction of
arrival parameter of a user equipment within the service range of
the local cell, wherein the direction of arrival parameter at least
includes downtilt information of a time-frequency resource block on
the antenna of the local cell with respect to user equipments
within the service range of the local cell; and
[0179] a determining unit, configured to determine, according to
the direction of arrival parameter obtained by the first obtaining
unit, optimal downtilt information of the time-frequency resource
block on the antenna of the local cell with respect to user
equipments within the service range of the local cell.
[0180] The first obtaining unit is specifically configured to
transmit channel state information reference signals of different
direction of arrival parameters to the user equipment within the
service range of the local cell on pilot resource elements within
the time-frequency resource block on the antenna of the local cell,
and receive a direction of arrival parameter that is returned by
the user equipment within the service range of the local cell and
corresponding to a reference signal whose signal received strength
measured on the reference signal is greater than a preset
threshold; or
[0181] the first obtaining unit is specifically configured to
transmit reference signals to the user equipment within the service
range of the local cell on pilot resource elements within the
time-frequency resource block on the antenna of the local cell in a
time division, frequency division, or code division mode; receive a
pre-code matrix of a channel state that is obtained by the user
equipment within the service range of the local cell by estimation
according to the reference signals; and obtain, by estimation, the
direction of arrival parameter of the user equipment within the
service range of the local cell according to the pre-code matrix;
or
[0182] the first obtaining unit is specifically configured to
obtain, by estimation, the direction of arrival parameter of the
user equipment within the service range of the local cell according
to an uplink channel quality measurement reference signal reported
by the user equipment within the service range of the local
cell.
[0183] Specifically, the obtaining module 301 further includes:
[0184] a second obtaining unit, configured to obtain a direction of
arrival parameter of a user equipment within the service range of
the local cell by estimation according to an uplink channel quality
measurement reference signal reported by the user equipment within
the service range of the local cell, wherein the direction of
arrival parameter at least includes downtilt information of the
time-frequency resource block on the antenna of the local cell with
respect to user equipments within the service range of the cell;
and obtain location information of the user equipment within the
service range of the local cell by calculation according to the
direction of arrival parameter; or
[0185] a third obtaining unit, configured to receive location
information that is obtained by a user equipment within the service
range of the local cell by performing positioning according to a
predetermined positioning technology.
[0186] A fourth obtaining unit is configured to receive downtilt
information, reported by at least one user equipment served by the
local cell, of a time-frequency resource block on an antenna of the
neighbor cell with respect to a predetermined user equipment, and
select downtilts, which are not recommended by the local cell for
time-frequency resource blocks on an antenna of a neighboring cell,
from the downtilt information of time-frequency resource blocks on
the antenna of the neighbor cell with respect to the predetermined
user equipment.
[0187] A receiving unit is configured to receive the downtilt
coordination information of the neighbor cell sent by the neighbor
cell.
[0188] A fifth obtaining unit is configured to obtain a direction
of arrival parameter of a user equipment within the service range
of the neighbor cell, where the direction of arrival parameter at
least includes downtilt information of a time-frequency resource
block on an antenna of the neighbor cell with respect to user
equipments within the service range of the neighbor cell, and
determine optimal downtilt information of the time-frequency
resource block on the antenna of the neighbor cell with respect to
user equipments within the service range of the neighbor cell
according to the direction of arrival parameter.
[0189] The fifth obtaining unit is specifically configured to
transmit channel state information reference signals of different
direction of arrival parameters to the user equipment within the
service range of the neighbor cell on pilot resource elements
within the time-frequency resource block on the antenna of the
local cell, and receive a direction of arrival parameter that is
returned by the user equipment within the service range of the
neighbor cell and corresponding to a reference signal whose signal
received strength measured on the reference signal is greater than
a preset threshold; or
[0190] the fifth obtaining unit is specifically configured to
transmit reference signals to the user equipment within the service
range of the neighbor cell on pilot resource elements within the
time-frequency resource block on the antenna of the local cell in a
time division, frequency division, or code division mode; receive a
pre-code matrix of a channel state that is obtained by the user
equipment within the service range of the neighbor cell by
estimation according to the reference signals; and obtain, by
estimation, the direction of arrival parameter of the user
equipment within the service range of the neighbor cell according
to the pre-code matrix; or
[0191] the fifth obtaining unit is specifically configured to
obtain, by estimation, the direction of arrival parameter of the
user equipment within the service range of the antenna of the
neighbor cell according to an uplink channel quality measurement
reference signal reported by the user equipment within the service
range of the antenna of the neighbor cell.
[0192] Specifically, the setting module 302 includes:
[0193] a first determining unit, configured to determine a range of
usable downtilts for time-frequency resource blocks on the antenna
of the local cell with respect to user equipments within the
service range of the local cell according to the downtilt
coordination information of the local cell and the downtilt
coordination information of the neighbor cell; and
[0194] a setting unit, configured to set, based on a preset rule,
the downtilt of a time-frequency resource block on the antenna of
the local cell with respect to the to-be-coordinated user equipment
according to the range of usable downtilts determined by the first
determining unit.
[0195] The first determining unit is specifically configured to
determine a range of optimal downtilts for time-frequency resource
blocks on the antenna of the local cell with respect to user
equipments within the service range of the local cell according to
optimal downtilt information, in the downtilt coordination
information of the local cell, of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell; and use a range of
downtilts within the range of optimal downtilts, excluding
downtilts which are in the downtilt coordination information of the
neighbor cell and are not recommended for a neighboring cell, as
the range of usable downtilts for time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell; or
[0196] the first determining unit is specifically configured to
obtain a distance between a base station of a local cell and a base
station of a neighbor cell by calculation according to location
information of the base station of the neighbor cell in the
neighbor cell coordination information and location information of
the base station of the local cell in the local cell coordination
information, and obtain the range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell by calculation according to the distance and a vertical
main beam width of the antenna of the local cell based on a
geometrical relationship; or
[0197] the first determining unit is specifically configured to
determine a range of optimal downtilts for time-frequency resource
blocks on the antenna of the local cell with respect to user
equipments within the service range of the local cell according to
optimal downtilt information, in the downtilt coordination
information of the local cell, of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell; obtain a set consisting
of neighbor cell downtilts whose use probabilities exceed a first
threshold according to use probabilities, in the downtilt
coordination information of the neighbor cell, of downtilts of the
antenna of the neighbor cell on time-frequency resource blocks;
according to location information of the base station of the
neighbor cell and location information of the base station of the
local cell, calculate a downtilt set B of the antenna of the local
cell with respect to geographical locations corresponding to the
set consisting of the neighbor cell downtilts; and use a range of
downtilts within the range of the optimal downtilts, excluding
downtilts in the set B, as the range of usable downtilts for
time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell; or
[0198] the first determining unit is specifically configured to
determine a range of optimal downtilts for time-frequency resource
blocks on the antenna of the local cell with respect to user
equipments within the service range of the local cell according to
optimal downtilt information, in the downtilt coordination
information of the local cell, of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell; according to location
information, in the downtilt coordination information of the
neighbor cell, of UEs within the service range of the neighbor cell
and location information of the base station of the local cell,
calculate a downtilt set C of the antenna of the local cell with
respect to the location information of the UEs of the neighbor
cell; or according to optimal downtilt information of
time-frequency resource blocks on the antenna of the neighbor cell
with respect to user equipments within the service range of the
neighbor cell and the location information of the base station of
the neighbor cell, calculate geographical locations corresponding
to the optimal downtilts, and according to the geographical
locations corresponding to the optimal downtilts and the location
information of the base station of the local cell, calculate a
downtilt set C of the antenna of the local cell with respect to the
geographical locations corresponding to the optimal downtilts; and
use a range of downtilts within the range of optimal downtilts,
excluding downtilts in the set C, as the range of usable downtilts
for time-frequency resource blocks on the antenna of the local cell
with respect to user equipments within the service range of the
local cell; or
[0199] the first determining unit is specifically configured to
determine a range of optimal downtilts for time-frequency resource
blocks on the antenna of the local cell with respect to user
equipments within the service range of the local cell according to
optimal downtilt information, in the downtilt coordination
information of the local cell, of time-frequency resource blocks on
the antenna of the local cell with respect to user equipments
within the service range of the local cell; according to
probabilities, in the downtilt coordination information of the
neighbor cell, that each time-frequency resource block on the base
station of the neighbor cell is assigned to different user
equipments, search for a user equipment whose probability of being
assigned with a time-frequency resource block of the neighbor cell
is greater than a second threshold, and according to location
information of the found UE and the location information of the
base station of the local cell, calculate a downtilt set D of the
antenna of the local cell with respect to the location information
of the found UE; or according to optimal downtilt information of
time-frequency resource blocks on the antenna of the neighbor cell
with respect to the found UE and the location information of the
base station of the neighbor cell, calculate geographical locations
corresponding to the optimal downtilts, and according to the
geographical locations corresponding to the optimal downtilts and
the location information of the base station of the local cell,
calculate a downtilt set D of the antenna of the local cell with
respect to the geographical locations corresponding to the optimal
downtilts; and use a range of downtilts within the range of optimal
downtilts, excluding downtilts in the set D, as the range of usable
downtilts for time-frequency resource blocks on the antenna of the
local cell with respect to user equipments within the service range
of the local cell.
[0200] The setting unit is specifically configured to obtain
optimal downtilt information of the to-be-coordinated user
equipment from the optimal downtilt information, in the local cell
coordination information, of time-frequency resource blocks on the
antenna of the local cell with respect to user equipments within
the service range of the local cell; traverse all usable downtilts
in the range of usable downtilts to find a usable downtilt that is
closest to the optimal downtilt of the to-be-coordinated user
equipment; and set the downtilt of the time-frequency resource
block on the antenna of the local cell with respect to the
to-be-coordinated user equipment to the usable downtilt that is
closest to the optimal downtilt of the to-be-coordinated user
equipment; or
[0201] the setting unit is specifically configured to traverse all
usable downtilts in the range of usable downtilts to find a usable
downtilt that allows the to-be-coordinated user equipment to have a
greatest signal received power, and set the downtilt of the
time-frequency resource block on the antenna of the local cell with
respect to the to-be-coordinated user equipment to the usable
downtilt that allows the to-be-coordinated user equipment to have
the greatest signal received power; or
[0202] the setting unit is specifically configured to traverse all
usable downtilts in the range of usable downtilts to find a usable
downtilt that allows a greatest signal-to-leakage-and-noise ratio,
and set the downtilt of the time-frequency resource block on the
antenna of the local cell with respect to the to-be-coordinated
user equipment to the usable downtilt that allows the greatest
signal-to-leakage-and-noise ratio; or
[0203] the setting unit is specifically configured to traverse all
usable downtilts in the range of usable downtilts to find a usable
downtilt that allows a greatest sum of
signal-to-interference-plus-noise ratios, and set the downtilt of
the time-frequency resource block on the antenna of the local cell
with respect to the to-be-coordinated user equipment to the usable
downtilt that allows the greatest sum of
signal-to-interference-plus-noise ratios.
[0204] In addition, the apparatus further includes a coordinating
module 303.
[0205] The coordinating module 303 includes a classifying unit,
configured to classify user equipments within the service range of
the local cell; and
[0206] a first coordinating unit, configured to assign a
time-frequency resource block on the antenna of the local cell to
the to-be-coordinated user equipment according to the
classification information of user equipments within the service
range of the local cell based on a fractional frequency reuse FFR
scheduling principle or a soft frequency reuse SFR scheduling
principle; or
[0207] a second coordinating unit, configured to assign a
time-frequency resource block on the antenna of the local cell to
the to-be-coordinated user equipment according to the
classification information of user equipments within the service
range of the local cell and the use probabilities, in the neighbor
cell coordination information, of downtilts on each time-frequency
resource block on the antenna of the neighbor cell based on a
self-defined dynamic scheduling principle.
[0208] The classifying unit is specifically configured to classify
user equipments within the service range of the local cell
according to the optimal downtilt information, in the downtilt
coordination information of the local cell, of time-frequency
resource blocks on the antenna of the local cell with respect to
user equipments within the service range of the local cell based on
a pre-defined assignment rule; or
[0209] the classifying unit is specifically configured to classify
user equipments within the service range of the local cell
according to the location information, in the downtilt coordination
information of the local cell, of user equipments within the
service range of the local cell.
[0210] By implementing the technical solutions of obtaining the
downtilt coordination information of a local cell and the downtilt
coordination information of a neighbor cell, and then setting,
according to the downtilt coordination information of the local
cell and the downtilt coordination information of the neighbor
cell, a downtilt of a time-frequency resource block on the antenna
of the local cell with respect to a to-be-coordinated user
equipment, the downtilt coordination information of the local cell
and that of the neighbor cell are referenced to for setting the
downtilt of the time-frequency resource block on the antenna of the
local cell with respect to the to-be-coordinated user equipment,
which avoids interference on user equipments within a service range
of the neighbor cell while ensuring signal received power and SINR
experience for user equipments within a service range of the local
cell.
[0211] All or part of content of the technical solutions provided
by the foregoing embodiments may be implemented by software
programming, where a software program is stored in a readable
storage medium such as a hard disk, a CD-ROM, or a floppy disk of a
computer.
[0212] The foregoing description is merely exemplary about the
embodiments of the present invention, but is not intended to limit
the present invention. Any modification, equivalent replacement, or
improvement derived within the spirit and principle of the present
invention shall fall within the protection range of the present
invention.
* * * * *